Graft copolymers for reducing the surface tension in polymer blends

Abstract

The invention relates to a graft copolymer of the general structure B-(A)nm, consisting of blocks of the two polymers A and B, which have different chemical compositions. One of the polymers is a polycondensation polymer, selected from the group consisting of polycarbonates, polyester carbonates, polyesters, and polyamides, and the other polymer is a polymerisate of at least one vinyl monomer. The invention is characterized in that (i) the average molecular weight of the block of polymer B Mn(B) equals at least 13 kg/mol, determined by a combination of gel permeation chromatography and NMR spectroscopy, (ii) the number of side chains in the graft copolymer ns equals at least 3 and maximally 15, determined by NMR spectroscopy, (iii) the average molecular weight of the block of polymer A Mn(A) equals at least 1.5 kg/mol and maximally 15 kg/mol, determined by a combination of gel permeation chromatography and NMR spectroscopy, and (iv) ns multipled by Mn(A) equals at least 13 kg/mol. The invention also relates to the use of the aforementioned graft copolymers in order to reduce the phase surface tension in mixtures containing the polymers A and B, to compositions containing the graft copolymers and the polymers A and B, and to molded bodies containing said compositions.

1 . A graft copolymer of the general structure B-(A), consisting of blocks of two polymers A and B of differing chemical composition, wherein one of the polymers is a polycondensation polymer selected from the group consisting of polycarbonates, polyestercarbonates, polyesters, and polyamides and the other polymer is a polymer composed of at least one vinyl monomer, 
       characterized in that
 (i) the number-average molecular weight of the block of polymer B M n (B) is at least 13 kg/mol, determined by a combination of gel-permeation chromatography and NMR spectroscopy, 
 (ii) the number of side chains in the graft copolymer n 5 , determined by NMR spectroscopy, is at least 3 and not more than 15, 
 (iii) the number-average molecular weight of the blocks of polymer A M n (A) is at least 1.5 kg/mol and not more than 15 kg/mol, determined by a combination of gel-permeation chromatography and NMR spectroscopy, and 
 (iv) n s  multiplied by M n (A) comes to at least 13 kg/mol. 
 
     
     
         2 . The graft copolymer as claimed in  claim 1 , wherein polymer A is selected from the group consisting of aromatic polycarbonates, aromatic polyestercarbonates, and aromatic polyesters. 
     
     
         3 . The graft copolymer as claimed in  claim 1 , wherein polymer A is an aromatic polycarbonate. 
     
     
         4 . The graft copolymer as claimed in  claim 1 , wherein polymer B is a polymer of one or more different vinyl monomers selected from the group consisting of styrene, styrene derivatives, acrylonitrile, acrylic esters, acrylic ester derivatives, olefins, maleimide, and maleimide derivatives. 
     
     
         5 . The graft copolymer as claimed in  claim 4 , wherein the vinyl monomers are selected from the group consisting of styrene, acrylonitrile, methyl methacrylate, glycidyl methacrylate, and olefins. 
     
     
         6 . The graft copolymer as claimed in  claim 1 , characterized in that the following features are present:
 (i) M n (B) is at least 23 kg/mol,   (ii) n s  is at least 6,   (iii) M n (A) is at least 4.5 kg/mol,   (iv) n s  multiplied by M n (A) comes to at least 13 kg/mol, and   (v) M n (A)·n 5 /[M n (B)+M n (A)·n 5 ] is in the range from 0.40 to 0.70.   
     
     
         7 . The graft copolymer as claimed in  claim 1 , wherein n s  is not more than 12. 
     
     
         8 . The graft copolymer as claimed in  claim 1 , wherein M n (B) is not more than 200 kg/mol. 
     
     
         9 . The graft copolymer as claimed in  claim 1 , wherein M n (A) is not more than 12 kg/mol. 
     
     
         10 . The graft copolymer as claimed in  claim 1 , wherein n s  multiplied by M n (A) is not more than 80 kg/mol. 
     
     
         11 . The graft copolymer as claimed in  claim 1 , wherein the architecture of the graft copolymer is selected from doubly terminally grafted and centrally grafted. 
     
     
         12 . (canceled) 
     
     
         13 . A polymer composition comprising polymers A and B and, as component C, a graft copolymer as claimed in  claim 1 ,
 wherein polymers A and B have the same chemical structure as the blocks of polymers A and B in the graft copolymer corresponding to component C.   
     
     
         14 . The polymer composition as claimed in  claim 13 , wherein the ratio of the mass fraction of polymer A in the polymer composition, based on the sum total of polymers A and B in the composition, to the mass fraction of the graft branches in the graft copolymer corresponding to component C is 0.6 to 1.4. 
     
     
         15 . A molded article comprising a composition as claimed in  claim 13 .